Electrodeposited metal layers with embedded particles are known. For example, hard material particles are embedded in electrodeposited nickel layers as a wear protection.
Thus, from DE 3503859 A1, it is known to embed boron nitride particles and silicon carbide particles directly in an electrodeposited nickel layer.
DE 10301135 A1 also describes the embedding of hard material particles in an electrodeposited nickel layer.
U.S. Pat. No. 4,479,855 A describes the embedding of silicon carbide particles in electrodeposited nickel. In this method, a complicated dispersing agent system is employed since hard material particles alone do not form a stable dispersion, and a uniform distribution of the particles in the resulting nickel layer can be achieved only by the dispersing agent system.
Due to the surface potential of hard materials, they are hardly or not at all dispersible in water and thus it has been necessary to date to keep them in dispersion with complicated dispersing agent systems.
Quite independently thereof, the coating of particles with silicates has also been known. For example, EP 0 492 223 A2 may be mentioned, which relates to silanized pigments and the use thereof for the inhibition of the yellowing of pigmented plastic materials, wherein the increase of the stability of pigment surfaces towards the action of air, oxygen, heat and light is addressed, and a chemisorption of silane compounds to pigments is mentioned, wherein said pigment coating is to be effected, in particular, with addition of solvents or other materials, such as coupling agents or carrier liquids, in an intensive mixer. Further, DE 19817286 may be mentioned, which relates to a multilayered pearlescent pigment based on an opaque substrate, this application discussing among others the pigmentation of bonds and security papers and packages as well as the laser labeling of polymeric materials and papers. In this document, it is proposed to coat gamma pigments having a particle size of from about 10 μm to cause them to show a particularly pronounced color flop, which means that the interference colors of the gamma are to depend very strongly on the viewing angle.
EP 0245984 A1 describes the coating of titanium dioxide particles with silicate. The addition of the silicate solution during the coating takes place without additional energy input at a pH that is substantially above the isoelectric point of titanium dioxide.
U.S. Pat. No. 6,440,322 B1 describes the coating of iron oxide particles with silicate.
DE 69708085 T2 describes the coating of oxide particles with silicon dioxide.